Squid.conf, few ways switcher, load ballancing.

Ok. I have question about Squid.conf and routing traffic between fev different proxy server, with almost parallel connection, connecting between host and one by one proxies listening at the same address but different port. Generally is hard to find any information at web about this tools.

Question is: It is possible connecting from one host to for example bing yachoo or another web site, using proxy switcher with one will be sending packages not from one IP, but using fev proxy servers alternately?

Some one tried doing it using squid? I have lulls if squid can do it.